Vehicles may use an engine drive system to drive various features in an internal combustion engine. For example, a typical engine drive system for a dual overhead camshaft arrangement includes a timing belt that engages various sprockets to rotate both camshafts and a crankshaft.
For example, U.S. Pat. No. 5,351,663 describes a torque transmission mechanism including a plurality of camshaft gears. The camshaft gears include multiple layers or interfaces with teeth for engaging with the teeth of another gear.
The inventors herein have recognized various issues with the above system. In particular, overlapping sprockets to couple a camshaft to the engine drive system increases wear of the overlapping sprockets due to the multiple interacting surfaces. Further, such overlapping sprockets are not durable to withstand high engine loads.
As such, one example approach to address the above issues is to indirectly couple a camshaft to the engine drive system via a meshed gear drive. In this way, it is possible to reduce the spacing between the camshafts, without overlapping sprockets.
Specifically, in one embodiment, an exhaust camshaft is directly rotatably coupled to the engine drive system and the intake camshaft is indirectly rotatably coupled to the engine drive system via a meshed gear drive. The meshed gear drive includes a first gear coupled to a sprocket of the engine drive system via a driveshaft. Further, the first gear is matingly coupled with a second gear to drive a rotation of the intake camshaft. This configuration enables the intake camshaft to be positioned between the exhaust camshaft and the driveshaft such that the shafts are horizontally coplanar. In this way, it is possible to reduce the spacing between the camshafts without the use of overlapping sprockets.
Note that various bands may be used, such as timing chain, a timing belt, or various other types of elastic and/or inelastic flexible bands. Further, the band may mate to toothed or un-toothed pulleys on the various shafts. Further still, additional bands may also be used, if desired.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.